Performance of Steam Displacement in the Kern River Field

Abstract

Oil recoveries of 50 to 70 percent of the original oil in place have result from steam-displacement pilots in the Kern River field. These recoveries correlated well with laboratory physical-model experiments. Both field and laboratory data show oil recovery to be a function of reservoir oil viscosity. Introduction This paper is an update of previous articles written on thermal-recovery operations in the Kern River field. It presents several steam-displacement pilots started in the field to investigate various sand members within the Kern River series. Experimental steamflooding data obtained from laboratory physical models are correlated with actual field results. The effects of oil viscosity, injection temperature, and injection rate on oil recovery are included. The Kern River field produces a 12 degrees to 16.5 degrees API gravity oil from 500- to 1,300-ft depths. The reservoir and fluid characteristics are very favorable to thermal-recovery methods. The average oil viscosity of 4,000 cp at the reservoir temperature of 90 degrees F is reduced markedly at higher temperature levels. Permeability and porosity are high and reservoir pressure is low. History of Development The Kern River oil field was discovered in the late 1890's by a hand-dug well at a total depth of 73 ft. Since that time, production from the Kern River field has depended greatly on economic conditions relating to the demand for heavy crude oil. It was not until the 1950's, when refining techniques were advanced, that the demand for heavy oils increased. These conditions provided the economic incentive for experimenting with new recovery methods. Thermal recovery in the Kern River field began with the use of bottom-hole heaters during the mid-1950's. Based on their success, thermal-recovery operations developed at a rapid pace. Table 1 shows the present status of Getty Oil Co. thermal operations in the Kern River field, where there are 668 developed steam-displacement patterns with more than 1,000 associated producing wells. Fig. 1 shows the location of these patterns in relation to Getty-owned property in the field. Present steam-displacement development property in the field. Present steam-displacement development is about one-third of full development. Steam stimulation played a very important role in increased oil production played a very important role in increased oil production during the early phase of thermal development. This process, involving short-term steam injections into producing wells, developed rapid results, but future response projections indicated it would play a somewhat minor role in the total ultimate oil recovery in the field. Steam displacement was initiated to recover ultimately a much greater portion of the oil in place. Steam displacement during 1973 accounted for 74 percent of the total production rate of 55,000 BOPD and is becoming the dominant recovery method for the future. The Kern River formation is composed of a sequence of alternating sand and shale members. These sand members are fine to very coarse with silt interbeds. Fig. 2 is a fieldwide stratigraphic cross-section showing the alternating sand and shale members. The structure of the Kern River field is a simple homocline dipping 4 degrees to the southwest. The horizontal scale on the cross-section has been compressed, which explains the exaggerated steeper dip shown. Considerable geologic study has gone into defining the continuity of each sand member. Detailed cross-sections have been developed for the orderly planning of displacement pilots and expansions. JPT P. 997